Child-resistant cap

ABSTRACT

A child-resistant closure for a container includes an inner cap retained in an outer cap, the outer cap being rotatable with respect to the inner cap; the inner cap having a gripping surface on a circumferential sidewall; the outer cap having a circumferential lateral wall defining elongate cutouts that expose the gripping surface, the cutouts being sized and spaced to provide adequate contact area between a typical thumb of an adult and the exposed gripping surface to allow removal of the closure from a container and inadequate contact area between a typical thumb of a child.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

FIELD OF THE DISCLOSURE

This disclosure pertains to child-resistant packaging and more particularly to internally threaded caps or closures that are highly resistant to removal from a container by a child, but which can be easily removed by an elderly, weak or infirm adult.

BACKGROUND OF THE DISCLOSURE

Child-resistant locking closures were invented in the 1960's, and have been widely used as a last line of defense against the risk of children ingesting dangerous materials. The Poison Prevention Packaging Act requires the use of child-resistant packaging for most prescription drugs, over-the-counter drugs, household chemicals, and other hazardous materials that could be dangerous for children.

There are now hundreds of child-resistant packaging designs available. Most of these designs require two dissimilar motions for opening, which are intended to be easy for adults, yet difficult for children. However, the U.S. Consumer Product Safety Commission has stated that there is no such thing as child-proof packaging. Thus, the objective is to design packaging that denies access to most children, while allowing access to most adults. Existing child-resistant packaging is reasonably effective at preventing most children from opening such containers, while allowing most adults easy access to the contents of such containers. However, because most of these designs rely on a disparity between the knowledge, strength and/or dexterity of the typical adult as compared with the typical child, there are precocious and/or unusually strong or dexterous children that will be able to open existing child-resistant packaging, and there are weak, elderly or infirm adults that will be denied access to the contents of child-resistant packaging.

Thus, there is a need for an improved child-resistant cap or closure for a container that allows fewer children to open the container and also allows more adults to open the container.

SUMMARY OF THE DISCLOSURE

The disclosed child-resistant internally threaded closure relies primarily, or at least in part, on a difference between adults and children other than knowledge, strength and/or dexterity. Rather, the disclosed child-resistant internally threaded closure relies on an anatomical differences between children and adults that is more reliable than the difference between the strength, knowledge and/or dexterity of children as compared with adults. In particular, the child-resistant closures described herein employ a design that takes advantage of the more consistent disparity between the width or surface area of the flesh covering the phalanges of fingers and thumbs of the typical adult as compared with those of the typical child. The fingers and thumbs are unique precision tools that apply grip force in a specific way that no other body parts or body surfaces can emulate to the same degree. The differences in bone size of the fingers and thumbs govern structural support for the surface area of the flesh to provide an adequate area of contact pressure coverage. The thumb provides the greatest area of contact pressure coverage. However, an adult with a sufficiently large index finger could open the cap by gripping with their index finger (although the thumb applies force more efficiently, making opening with the thumb feel easier). Throughout the remainder of this disclosure, reference will be made to application of gripping forces using the thumb. However, the disclosed design is not limited to the thumb disparity between adults and children, but instead applies to the fingers as well.

The disclosed child-resistant closure has an inner cap retained in an outer cap. Gripping surfaces on a sidewall of the inner cap are exposed through cutouts in the outer cap. The cutouts are sized and spaced so that a thumb of a typical adult can contact an area of the gripping surface that is sufficient to provide the force needed to remove the closure from the container, whereas the thumb of a typical child is too small to contact a sufficiently large area of the exposed gripping surface to allow removal of the closure from the container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a child-resistant closure in accordance with this disclosure.

FIG. 2 is a top perspective view of the inner cap of a child-resistant closure in accordance with this disclosure.

FIG. 3 is a bottom perspective view of the inner cap of the child-resistant closure.

FIG. 4 is a top perspective view of the outer cap of the child-resistant closure.

FIG. 5 is a bottom perspective view of the outer cap of the child-resistant closure.

FIG. 6 is an exploded perspective view showing threading engagement between the child-resistant closure and a container.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Shown in FIG. 1 is a child-resistant closure 10 in accordance with this disclosure. Closure 10 includes an inner cap 12 (shown in FIGS. 2 and 3), and an outer cap 14 (shown in FIGS. 4 and 5). As shown in FIG. 1, inner cap 12 is nested within and retained by outer cap 14.

Outer cap 14 includes a lip portion 16 that extends radially inwardly of a lateral wall 28 that depends from an upper wall 19. In the illustrated embodiment, lip portion 16 is located at a bottom edge of wall 28, but could conceivably extend from an interior side 29 of wall 28 disposed in spaced relation to the bottom edge of wall 28. Lip portion 16 retains inner cap 12 within outer cap 14 so that it cannot be easily separated from the outer cap when the closure 10 is completely removed from a container.

Inner cap 12 includes a top wall 41 and a depending circumferential side wall 20 having an interior surface 21 provided with internal threads 34 for engaging external threads 36 on a container 22 (see FIG. 6), and an exterior surface 23 provided with gripping features 32. In the illustrated embodiment, gripping features 32 comprise a plurality of parallel elongate protuberances or ribs that extend vertically (i.e., parallel to the screw axis of cap 12), however, other types of gripping features can be employed, such as hemispherical bumps, knurls, or the like.

The lateral wall 28 includes an upper elongate cutout section 24 and a lower elongate cutout section 26 that is spaced from the cutout 24 and separated from cutout 24 by a bridge portion 30. Cutouts 24 and 26 expose gripping features 32 on exterior surface 23 of sidewall 20 of inner cap 12. The cutouts 24 and 26 are sized so that substantially the entire surface of the thumb of a typical adult can contact either the exposed gripping features 32, whereas the thumb of a typical child would contact a substantially reduced area of the exposed gripping surfaces. Therefore, a child would need to apply substantially more thumb pressure in order to apply the amount of force needed to unscrew closure 10 from a container 22. For example, a typical adult has a distal phalanx portion of the thumb that is about 30 mm long and about 20 mm wide, whereas a typical child might have a distal phalanx portion of the thumb that is about 25 mm by 15 mm. Thus, if the cutouts 24 and 26 are sized to have a length along the circumference that is about 30 mm and widths that are each about 6 mm with the bridge having a width of about 8 mm, the thumb of the typical adult would contact about 360 square millimeters of the exposed gripping surface, whereas the thumb of the typical child would contact only about 175 square millimeters. Therefore, if the closure is designed so that a predetermined amount of pressure must be exerted on the gripping surface to allow a typical adult to remove the closure 10 from a container 22, a typical child would be required to apply more than twice the amount of pressure needed by the typical adult to remove the closure. Stated differently, an adult-size thumb can wrap around the bridge 30 to apply pressure and torque to inner cap 12, whereas a child-size thumb cannot wrap around bridge 30 to allow sufficient contact with the exposed gripping surface.

The amount of effort needed to open the container 22 can be controlled by appropriate design of the threads (e.g., pitch, lead, thread angle, thread depth, etc.), and by providing the closure with a stop 46 that prevents over-tightening of closure 10 onto a container 22. Stop 46 is located on the interior surface 21 of wall 20 of inner cap 12, and includes a bottom or stop surface 47 that engages an upper edge surface 50 of bottle 22 to ensure that the amount of torque or force needed to remove closure 10 does not vary appreciably after it is tightened onto bottle 22.

In the illustrated embodiment, inner cap 12 is provided with one-way ratchet ramps 40 on the upper surface of top wall 41. Ramps 40 each include a sloped surface 52 and a stop surface 54. Outer cap 14 is provided with one-way ratchet ramps 42 on bottom surface 44 of upper wall 19. Each of ramps 42 includes a sloped surface 56 and a stop surface 58. In the illustrated embodiment, clockwise rotation of outer cap 14 causes outer cap 14 and inner cap 12 to lock and rotate together when stop surfaces 54 and 58 contact. Counterclockwise rotation of outer cap 14 causes caps 12 and 14 to slip or slide past each other as sloped surfaces 52 and 56 engage, causing only outer cap 14 to rotate unless adequate pressure is applied to the surfaces of inner cap 12 exposed through cutouts 24 and 26.

The above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined with reference to the appended claims along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur, and that the disclosed systems and methods will be incorporated into such future embodiments.

All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc., should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. 

What is claimed is:
 1. A child-resistant closure for a container, comprising: an inner cap rotatably retained within an outer cap; the inner cap including a top wall and a depending circumferential side wall having an interior surface and an exterior surface, threads on the interior surface of the side wall of the inner cap, and gripping features on the exterior surface of the side wall of the inner cap; and the outer cap having an upper wall and a depending lateral wall, the lateral wall having an upper elongate cutout section exposing gripping features on a first section of the exterior surface of the sidewall of the inner cap, and a lower elongate cutout section exposing gripping features on a second section of the exterior surface of the sidewall of the inner cap, the upper cutout and the lower cutout together defining a bridge portion of the lateral wall extending between the upper and lower cutouts, the bridge portion covering a section of the sidewall between the upper and lower cutouts.
 2. The closure of claim 1, wherein the inner cap is rotatably retained within the outer cap by a circumferential lip portion that projects inwardly from an interior surface or lower edge of the lateral wall of the outer cap, and supports a lower edge of the side wall of the inner cap.
 3. The closure of claim 1, wherein the gripping features are a plurality of ribs.
 4. The closure of claim 1, wherein an upper surface of the top wall of the inner cap includes a first one-way ratchet ramp, and a lower surface of the upper wall of the outer cap includes a second one-way ratchet ramp, whereby the first one-way ratchet ramp and the second one-way ratchet ramp are engageable with each other to allow the inner cap and the outer cap to be rotated together when the closure is screwed onto a container, and the first one-way ratchet ramp and the second one-way ratchet ramp allow the outer cap to rotate freely with respect to the inner cap when the outer cap is rotated in an opposite direction unless there is a predetermined amount of contact between the exposed exterior surfaces of the side wall of the inner cap and the thumb of a person rotating the outer cap.
 5. The closure of claim 1, wherein an upper surface of the top wall of the inner cap includes a pair of one-way ratchet ramps, and a lower surface of the upper wall of the outer cap includes a second pair of one-way ratchet ramps, whereby the first pair of one-way ratchet ramp and the second pair of one-way ratchet ramp are engageable with each other to allow the inner cap and the outer cap to be rotated together when the closure is screwed onto a container, and the first pair of one-way ratchet ramp and the second pair of one-way ratchet ramp allow the outer cap to rotate freely with respect to the inner cap when the outer cap is rotated in an opposite direction unless there is a predetermined amount of contact between the exposed exterior surfaces of the side wall of the inner cap and the thumb of a person rotating the outer cap.
 6. The closure of claim 1, wherein the interior surface of the inner cap includes a stop that prevents the inner cap from being over-tightened onto a container, thereby facilitating removal of the closure from a container when pressure from an adult thumb is applied to the surfaces of the exterior surfaces of the sidewall of the inner cap exposed through the upper and lower cutouts of the lateral walls of the outer cap. 